AS THE most-decorated Olympian walked away last Saturday, he turned to gaze over his shoulder one last time—not at a swimming pool but at a journalist who was asking other members of the 4 √ó 100 medley relay team whether they thought their renowned teammate was really retiring. "Oh," said Michael Phelps, barely breaking stride, "I'm done."

A butterflyer—at least he swam the butterfly in his final race—was free.

Ever since going 8 for 8 in '08, Phelps's practiced response to questions about his legacy always revolved around a variation of being "the first Michael Phelps." Now he must be the second Michael Phelps, a daunting proposition given the fabulous first act. At age 27 he exits the Olympics with 18 gold medals, two silvers and two bronzes. Phelps might no longer be at the top of his game, but he remains at the zenith of his sport, having won two individual golds (100 fly and 200 IM), two relay golds and the pair of silvers in London. "Watching Michael swim is beautiful," said Missy Franklin, who won four gold medals in London. "Seeing what he does and how he moves through the water, you can tell that he's meant to do it." After the final swim—he turned a .21 of a second deficit into a .26 lead in the third leg—swimmers from other nations began approaching Phelps to shake his hand as if they were in a receiving line at a wedding. Or a wake.

The lingering question is whether swimming will miss Phelps more than Phelps will miss swimming. The sport will continue to stamp out stars—of the 21 Americans to win medals in the pool, 10 were younger than 24—but his final week seemed like a death in the FINA family. An elegiac Alain Bernard, one of the principal antagonists in Phelps's sweeping Olympic saga, the French 4 √ó 100 freestyle anchorman that Jason Lezak miraculously caught to make Phelps's golden streak in Beijing possible, told SI, "What he has done in the sport is extraordinary. He intimidated me.... He's the best swimmer in history."

If Phelps were a country, his 18 golds would rank among the top 40 in the 116-year history of the modern Summer Games. Through Sunday, he was just two behind Ethiopia, and if you reunited the Czech Republic and Slovakia, Phelpslandia would have a one-gold edge.

"I told myself I never wanted to swim when I'm 30," Phelps said. "That would be in three years. I don't want to swim another three years. I've been able to do everything I've wanted. I've been able to put my mind to the goals I've wanted to achieve, and Bob [Bowman, his coach] and I have somehow managed to do every single thing. And I think if you can say that about your career, there's no need to move forward. Time for other things."

He is thinking about doing a cage dive with great white sharks in the company of his new buddy, 20-year-old Chad Le Clos, the South African who was the last swimmer to beat Phelps, in the 200 butterfly on the fourth night of the Games. Phelps is also thinking about food, relieved that he can eat like a civilian, free of his famous mega-breakfasts and 10,000-calorie-a-day needs.

Wistful and relentless by equal measure, he stopped to smell the English roses along the way to his swimming dotage. He was less self-absorbed, more engaged than he had been in Beijing. During the Americans' pre-London camp in Vichy, France, Phelps even took some turns on a waterslide in the training complex. Phelps's U.S. teammate Allison Schmitt says he hung out in the cafeteria in the athletes' village longer, lingering over meals and chatting with anyone who approached. Phelps might not have been the elder statesman of USA Swimming, but he was the high-fivin', back-slappin' older brother.

"I wanted to change the sport and take it to a new level," Phelps said. "That was a goal of mine. If I can say I've done that, then I can say I've done everything I've wanted to do in my career. This sport has done so much for me, and I'll continue to give back as much as I can."

As he enters the second act of a unique American life, Phelps should have time to keep up with the journal he started this year. Asked how he might summarize his final Olympics, Phelps replied, "I can sum it up in a couple of words: I did it."

SI.COM

The 22-medal career of Michael Phelps in pictures at SI.com/olympics

PHOTOPhotograph by HEINZ KLUETMEIER

Gold Mettle Phelps went from pool to podium six more times in London, the last two times on top, to cap the greatest-ever Olympic career.